Production of connecting-rods and similar machine parts



OAKLEY l PRODUCTION 0F CONNECT'ING RODS `ANI) SIMILAR MACHINE PRTS.

APPLICATION `FILED MAY 29, i920.

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JI TTUIM'EV 'I nu 30ml' OAKLEY, 0F SPRINGFIEL), 'MASSACHUSETTS ASSIGNORTO BA'USH MACHINE TOOL COMPANYQA CGRIPRATION OF MASSACHUSETTS.

PRODUCTION OF CONNEGTINGr-RODS AN D SIMILAR MACHINE PARTS.

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l T all whom it 0mg concern.'

Be it known that l, JOHN OAKLEY, a citi- `Zen of the Kingdom of GreatBritain, and

resident of Springfield, Massachusetts, have invented certain new anduseful Improve-y ments in the Production of Connecting-Rods and SimilarMachine Parts, of which the following is a specification.

My invention provides an improved'connecting rod or similar machine parthaving a rotary or oscillatory connection with adjacent parts of themachine and subjected to various strains in use, and is directedparticularly to the connecting rods between the pistons and the cranksof an automobile or similar internal combustion engine; the improvement'being in the composition of such rods and in their combination withother parts.

For many years aluminum and alloys thereof have been used to a greateror less extent, but no such alloy has been thought to be adapted for usein the making of connecting rods and the like, having the necessaryphysical qualities to make a connecting rod which should be strongenough to stand the shocks and strains of use and which could be readilymachined to the accuracy required in practice. I have found that thereare certain alloys of aluminum which by an -appropriate method ofmanufacture and treatment can be made into connecting rods which willhave the durability and strength of steel andl will be very vmuchlighter with little or no increase in cost of the finished article,taking into consideration the great l saving in the cost of cutting ormachining.

i ordinary l have found also that such metal is peculiarly useful inthat it can be used without babbitt-ing its hearings on the wrist pinand crank pin, being itself a good bearing metal with a hi herresistance to abrasion than abbitt metal. rlhese qualities make such aconnecting rod greatly desired @for automobiles where lightness is ofimportance in proportion of strength.. The connecting rods inautomobiles are sub]ected at each operation to a downward blow 4at theirupper ends from the sudden expansion in their cylinders and to an upwardblow from the crank pins against the resistance of the gas to becompressed, and being of considerable length they are liable also to thebendving strain on a columnar structure. Thus they have to be madestrong and of a considerable cross-section. so that a reduction inSpecification of Letters Patent. Paintgd Digg, '20), 1:92p

.application med may 2a,

1920. .Serial No. 385,174.

the unit weight of the metal employed means a considerable reduction inthe total weight. When we add the comparatively frictionless bearingquality of the metal it will be seen useful in producing a good polishedwearing surface. This alloy is cast into ingots, worked as by rollingor` forging into billets and then cut and further forged, preferablydrop-forged,- into blanks. Such forging or' otherwise working of themetal increases its tensile strength (which measures its resistance tobending) as, for example, from 27,000 pounds per square inch to 36,000or as high as 40,000 pounds.

The forged blanks are then'heated to a temperature approximating' 500 to525 degrecs centigrade and then quenched. lt is found that this heattreatment increases the physical qualities very substantially. `Forexample, alloy having beforehand an ultimate tensile strength of 36,000pounds per square inch, will have its strength increased to 55,000 or60,000. The elastic limit will be raised from 25,000 pounds per-squareinch, to 36,000, the. elongation from 2 to 20% and the reduction of areaunder strain from 6 to 40%. rlFhere is thus produced a metal having thestrength of steel with the comparatively frictionless quality of goodbearf the ends to fit their pins. The aging of the metal after the heattreatment serves also to bring it to a condition in which it machines orcuts better than before. The mach'ining may be done before the aging iscomplete lbut it can. be done better afterward. The ease with :which themetal can be machined is an importantconsideration in -economy -of theproduct. metal itself costs several times as much as Although the Isteel, yet the machining operations `on a connecting rod will cost somuch more for steel than for this improved alloy as to bring the totalcost of manufacture of the alloy con.

necting rod to a point which makes it a commercial compet-itor of alsteel rod.

There areconsiderable variations possible in the composition of thealuminum alloy and in the proportions of' the components. The importantthingfis to use such an alloy as will be capable of transformation byhea treatment into a metal of comparativel.A high strength, and elasticlimit, though it consists chiefly of `aluminum and weigh little morethanaluminum.

The aluminum alloys above referred to andthe heat treatment thereof havebeen for connecting rods or any similar machine parts, althoughthroughout this period numerous efforts have been inade especially inthe automobile industry tc, lighten the en-l gine and to cheapen it by areduction in the cost of bearings.` l .I have found by experiment thatthe connecting rods for such engines made as above described havenotonly the knownfiqualities of lightness and strength but alsoa quiteunexpected resistance to bending undenthe shock of `compressive 'strainsand a resistance to abrasion and a smoothness or lack of friction which`make them not only practicable but very much superior to connect# ingrods of steel; and the economy involved -in Amachining operations hasbeen unexpectedly great and sufficient to make them a commercialsuccess.

Another. feature of unexpected but'considerable importance is thesilence with which -they work in' engagement with the pins at either`end. It is a common criticism of automobile engines, that, especiallyafter a short. period of use7 the wear of the pins or of their' bearingsin the connecting rods causes a tapping in the en ine. With my improvedconnecting rods t e noise of engagement fof the parts is very greatlyless than with other metals. i

The best results have been obtained with an excessive working of thealloy in making the billet or, the blank, and the alloy referred tolends itself advantageously to such operations. For example, in themaking of the'connecting rods referred to I have rolled and forged themetal down to one-thirdor one-fourth of the original cross-section. Thishas produced a dense, tough, fibrous structure excellently adapted foruse in con-v necting rods and similar parts and well capable of beingcut readily by ordinary steel cutters which could not possibly beused'lfor cutting hardened steel. i

T he accompanying `drawings illustrate a connecting rod made inaccordance with my invention, Figure 1 being a side elevation A with theyends Ain section and Fig. 2 being a transverse longitudinalsection. n

The connecting rod is formed withthe usual web 1 and flanges 2 and boss3 at' its upper end apertured to receive the wrist pin 4 connected tothe piston of the engine. At its lower end is a larger boss 5 withflanges 6 for attachmentto the flanges 7 of a cap "8, the boss and capbeing bored to provide a circular opening for the crank 9.

The pins 4 and 9 are indicated as of steely but they may be made ofVAother metal and even of the same aluminum alloy as the connecting rod,it being a peculiarity of this alloy that the friction betweentwo`pieces of the same -allcy is no greater than it is between thisalloy and steel; contraryto thev general rule that friction is greaterbetween two pieces of the samemetal than between two pieces of differentmetals.

` The cap 8 is preferably made of the same aluminum alloy as theconnecting rod proper, asl indicated .on the drawing, but

'this cap also may be made of other metals.

The hub 3 is bored toa closeV working t for the pin 4, without theintermediation of the babbitt or bearing metal usually linterposedbetween such parts in the better class of machines. I fhave foundthatwith thisA aluminum alloy the. bore can be made very exact and smoothand the bearing end of the rod can oscillate on' the pin with thesameease as a well babbitted bearing. Any usual or suitable arrangement ofoil grooves may be provided. The lower end of the rod has a similarbearing fit on the crank pi11` and permits the same smoothand easyrotation of one part' with relation to theother; Even when theparts'wear in use suiiiciently to produce a slight play of the pins intheir bearings, the contact of the pins with the rod of this alloy willbe found to make less noise than in the case of most similar bearings.

'In the manufacture of this connecting rod the rough forging will be ofexcessive size so as to permit the planing and boring to exactdimensions and finish on those faces where an exact fit or a smoothfnishis dethe bosses 3 and 5 and the interior bores-of these parts andpreferably also the outer faces and edges of the flanges 2. For thesired; such for example as the end faces of cap 8 the interior-bore andthe bearings for the` bolts and nuts and also the side edges, (right andleft edges in Fig. 2) should be machined to an exact dimension. And themeeting faces of the boss 5 and the lcap l8 should also be finishedexactly. All these machining operations are accomplished With thegreatest ease with this aluminum alloy; and thereby a great saving incost is effected as compared with similar operations on steel connectingrods.

An important advantage of the use of this connecting` rod for engines isthe extremely smooth and rapid acceleration and retardation of theengine and of the rapidly reciprocating parts thereof, owing to thelessened inertia and momentum by the great elimination of dead weight;such elimination being as highl as 6() or 'TO per cent. over connectingrodsand similar reciprocating parts' now commonly used.

Though l'have described with great particularity of detail aspecificdesign of connecting rod and a particular composition and method ofmanufacture, yet it will beV understood that the. design may be variedmay be departed from by those skilled in the art Without departure fromthe inven,- tion vas defined in the following claims.`

What I claim is: v f

1. A connecting rod or lthe like made of an' aluminum alloy of the classdescribed consisting mainly of aluminum so as to be approximately aslight as this metal and which has been Worked and heat-treated toincrease its density, tensile strength and elastic limit.

2. A connecting rod or the like made of an aluminum alloy of the classdescribed consisting mainly of aluminumso as to be approximately aslight as this metal and which has been Worked and heat-treated toincrease its density, tensile strength and elastic limit, in combinationWith a pin having a bearing in one end of said rod and which has beenWorked and heat-treated to increase its density, tensile strength andelastic limit, in combination with a cap of the same alloy Worked andheat treated in the same vay, the contacting faces of thel rod and caprespectively being machined to a perfect fit on each other.

Il. A connecting rod or the like composed of analuminum alloy of theclass described, forged and heat-treated' and then machined.

5. A connecting rod or the like composed of an alloy including aluminum,magnesium, manganese and copper and comprising about 94% aluminum andabout 0.5% magnesium, which alloy has been subjected to excessiveWorking and has been heated to a temperature approximating 500 to 525degrees centigrade and then quenched and machined. A

6.' A connecting rod` for connecting vthe pistons of internal combustionengines to the cranks thereof and having bearings at its ends forengagement with a ivrist pin and a crank pin respectively, saidconnecting -rod being made of an aluminum alloy of the class describedconsisting mainly of aluminum so as to be approximately as light as thismetal and which has been worked vand heat-treated to increase itsdensity, tensile strength. and elastic limit.

ln witness whereof, lf .have hereunto signed my name. l

JDHN OAKLEY.

